Means for supplying heat to the mixture delivered to internalcombustion engines



N 1929- B. BANNISTER I ,735,720

MEANS FOR SUPPLYING HEAT TO THE MIXTURE DELIVERED T0 INTERNAL COMBUSTION ENGINES Filed April 3 1926 Patented Nov. 12, 19239 BRYANT BANNISTER, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO BANNISTER M0- TOR APPLIANCE OOMPANY, OF PENNSYLVANIA OF PITTSBURGH, PENNSYLVANIA, A CORPORATION MEANS FOE'SUPPLYING HEAT TO THE MIXTURE DELIVERED-TO INTERNAL- COMBUSTION Application filed April 3,

- This invention relates to the conditioning of the mixture of liquid fuel and air delivered to internal combustion engines and particularly to means for transferring heat from the exhaust gases of automotive engines to the combustible mixture supplied to such engines. The usual fuel supply system of modern internal combustion engines applied to automotive service comprises, first, a carbureter for proportioning the liquid fuel to the air making up the combustible mixture and, second, an intake system or manifold which conveys the carbureted mixture or charges thereof to-the engine cylinders. v Aside from obtaining proper proportioning of the liquid fuel and air composing the combustible mixture, it is important to heat or condition the mixture before eflicient combustion can be obtained. The extreme range in vaporizing characteristics of the difierent fuels now on the market does not bother the carbureter designer, but it does introduce some serious difiiculties for the designers of the intake systems and the engines themselves.

Much progress has been made in the design of combustion chambers to meet the wide range of conditions, and many schemes have been proposed, andmany have been tried' out for heating or conditioning the mixture in its passage from the carbureters to the combustion chambers. I-refer to such schemes as stoves applied to the exhaust gas systems for preheating the air, exhaust gas jackets for heating parts of the intake system, ingeniously located contacts between the exhaust and intake systems which present hot spots for impingement of the mixture and combinations of these schemes, none of which, however, have successfully solved the prob- ]em.

The driver of an automobile (I use the term automobile as inclusive of all automotive devices) usually does not associate his engine troubles with the fuel intake system.

Automobile engine designers, however, do,

since they realize that crank case dilution (which is a direct result of poor mixture con ditioning) contributes largely to loose en- 1926. Serial No. 99,550.

vapors which are produced by supplying the latent heat of vaporization to the li'uid, converting it into a gas. It is because 0 this fact that much difficulty is experienced in starting and warming up in coldweather. It is now the usual practice to abnormally increase the quantity of liquid fuelduring starting and warmin up, but only the li ht components of the uel are vaporized bef ore combustion starts. Some of the heavier components pass I down the cylinder walls into the crank case and some vaporize during combustion and by making the mixture too rich, retard combustion.

Second. The mixture must be brought to normal working condition in the shortest pos sible time after the engine is started. This is important in order to avoid the use of excessive fuel during the warming up period. The unvaporized and unburned fuel reaching the crankcase of'the engine, carries with it particles of dirt from the combustion chamber which seriously impairs lubrication; and

Third. During periods of operation when maximum power is not required of the engine, maximum economy should be obtained and when maximum power is required, it should be obtained with good'economy.

The present day methods of preheating the air, of directing the mixture into contact with a hot spot and the other numerous schemes now made use of cannot possibly meet the requizl'ements for all conditions of speed and loa e If the amount of heat. provided for the ditions (this is the usual method of design) to 12()0 F. These gases the amount of heat supplied during warming verse section through the parts shown in up periods is entirelyinadequate and the Fig. 1.

amount of heat supplied during heavy loads is In Figs. 3 and 4, I have illustrated another excessive. On the other hand, if the heat proform of device for carrying my invention into vided is correct for maximum loads, there 'is, effect in an engine in which the exhaust mania decided deficiency for warming up periods fold is located above the inlet manifold. Fig. and for normal running. This can be readily 3 is a longitudinal and vertical section appreciated when it is understood that the through such manifolds and shows the heater gases exhausted from average automobile enelement applied thereto. Fig. 4 is 'a transgines vary in temperature'from about 400 F. verse section through the elements illustrated are used for prein Fig. 3. Figs. 5 and 6 are vertical sectional heatiifithe aiiaand for heating the hot spots and transverse views respectively, of a heater referred to so that the temperatureof the hot element for use in carrying out a modificaspots follow this range in temperature 'quiteswt-ionpf my heater element, like the heater eleclosely and necessitate hot stove and hot spot Inent illfitrated inlligs. 1 and 2, is particu- 3o proportions that are about right for normal larly applicable to engihesinwhichi'he inrunning but entirely too small for starting let manifold is located above the exhist n and warming up and entirely too large for manifold. a

hard pulling.

Some attempts have been made to automatically; compensate for the range in exhaust temperatures by using thermostats etc., but these attempts, so far as I am aware, have been complicated and have not been satisfactory. n

An object of this invention is to provide a simple means or apparatus for transferring heat from the gases exhausted from an internal combustion engine to the mixture of liquid fueland air entering the engine in such manner that the temperature of the mixture decreases as the load on the engine increases and increases as the load on the engine decreases;

A further object of this invention is to provide a means by which advantage is taken of the inherent pressure-temperatureQcharacteristics of a confined body of vaporizable fluid for transferring heat from the hot exhaust gases of an internal combustion engine to the mixture of liquid fuel and air delivered to the engine whereby the temperature of such mixture decreases as the load on the engine increases and increases as the load on the engine decreases.

I attain the above as well as other objects by means of the devices or apparatus for carrying the same into effect which I have described in the specification and illustrated in the drawings accompanying and forming part of this application.

- My novel device for supplying heat to the mixture of liquid fuel and air delivered to the cylinders of internal combustion engines is applicable to engines of different designs and to engines in which the inlet-and exhaust manifolds are variously arranged.

In Figures 1 and 2 of the drawings, I have illustrated one form of device for carrying my invention into effect in connection with an engine in which the inlet manifold is' located above the exhaust manifold. Fig. 1 is a? longitudinal and vertical section of such manifolds with my heater element incorporated in the manifolds and Fig. 2 is a. trans- Since a large supply of heat is available in the exhaust gasesof engines of the type in connection with which this invention is of especial value, I prefer to utilize a portion of this waste heat and have, therefore, illustrated and will describe my method in connection with structures for utilizing such heat without any idea, however, of definitely limiting my invention.

This invention broadly consists in. transferring heat to the mixture of liquid fuel and air delivered to engines of this type from the waste gases of combustion exhausted from such engines in such manner that the temperature of such mixture decreases as the temperature of the exhaust gases increases, and increases as the temperature of such gases decreases. The devices or means for carrying this invention into'efiect consists of a relatively thin walled, metal, tubular element which is closed or sealed, contains a relative- -ly small amount of vaporizable liquid and which is located partly within the exhaust system and partly within the intake system of the engine.

This tubular element is of such form and is soarranged as to project into the inlet manifold in such a way that the mixture traversing the passage is caused to contact therewith. Another portion of said tubular member (and this is preferably the lowest portion) is arranged to project into the exhaust passage or manifold of the engine.

It is conceivable that under certain circumstances it may be desirable to have the portion of this tubular element or member which is located outside of the inlet manifold heated by other means than the exhaust gases. For instance, it might be desirable to have a separate heater for this purpose. Again, it may be desirable under certain conditions to apply an electric heating element to the portion 125 1 of the tubular member located outside of the for use while starting the eninlet manifold,

gine when cold.

It will be seen that the principle of this invention can be applied in various ways, but

' ent forms of devices suitable for different types of engine manifolds.

In Figures 1 and'2, 10 designates an inter nal combustion engine inlet manifold and 11 an exhaust manifold. 12 is the ring heater towhich Ihave heretofore referred as the tubular member or element. This may be constructed from a piece of seamless tubing rolled into ring form with the ends thereof slightly telescoped and welded together.

Where the inlet manifold is located above the exhaust manifold as in Figs. 1 and 2, the two manifolds may be made as a single casting with the ring cast in place.

As shown in Figs. 1 and 2, the inlet portion 10 is provided with a flanged, tubular extension 13 by means of which the carburetor 'or other mixture forming device, not shown,

. may be connected thereto by means of an elbow 14, as is now usual.

' In the inlet portion 10 and. below that portion of the ring locatedtherein, there are twosemi-circular platEs or bafile walls '15. These walls are concentric with the ring 12 and are spaced a slight distance apart as shown in Fig. 2 to provide a relatively narrow semicircular slot 16 through which the mixture from the charge forming device must pass on its way into the inlet portion 10 proper. This slot is located directly in line with that portion of ring 12 which is above the same.

After the ring is formed up and welded, the air contained therein is preferably withdrawn through a small opening formed for that pu rise and a small quantity of fluid, prferab y water, is introduced, after which the ring is entirel sealed. The quantity of water to be intro uced is determined by the pressure which 'it is'desired to carry within the ring.

In Figs. 3 and 4, 17 denotes an inlet manifold and 18 an exhaust manifold located above the inlet manifold. In such an arrangement where the inlet manifold is located below the exhaust manifold, the ring form of heater does not lend itself as readily as the form shown in Figs. 3 and 4.

In this form, while the heater element is tubular and has its ends closed, it is of substantially L form having one long and one short leg. The long leg 19 is positioned along the median line of the inlet manifold above intake 20, while the short leg 21 is located within the downtake 22 connected to the exhaust manifold. In the form shown in Figs. 3 and 4, it is not necessary to cast the heater element in the manifold elements. The manifolds can be provided with bosses, if desired,

ing slot 16.

which can have holes eithercored or drilled in them, to receive the heater element. After the heater element is placed in position, it .can be welded to the bosses in any well-known manner. I

When the form of heater element shown in Figs. 3 and 4 is used, it will be evacuated in the same manner as the ring form and will have a relatively small amount of water introduced'and sealed therein.- The water in thgxt hree heater elements shown is indicated at In the heater element shown in Figs. 5 and 6, a baflle23 is shown, for preventing circulation within the ring.

Operation [therein into steam and the ring will present a hot surface against which the mixture of fuel and air is directed by annular The pressure of the steam will depend upon the heat imparted to the ring, the volumetric capacity of the ring and the quantity of water within the ring. If we assume that the volumetric capacity is 23 cubic inches and that the desired pressure to be maintained within the ring is 50 lbs. per square inch gauge, the ring should contain .002 lbs. of water. If the ring re'ceivessufiioient heat from the exhaust gases to maintain a steam pressure of 50 lbs. the temperature will be approximately 298 F.

With the form of ring shown in Figs. 1 and 2 (with no constriction therein) it is possible for the exhaust gases to supply heat at a greater rate than can be withdrawn by the incoming mixture of liquid fuel and alr. Under this condition, the steam will become superheated as soon as all the water is evaporated, and the hottest steam will be wit in that portion of the ring which is located within the, exhaust manifold. In the top of the ring or in that ortion which is located within the inlet manifold where heat the. temperature will be somewhat reduced. To illustrate the action, let us assume that the pressure is 50 lbs. per square inch within the ring and that the temperature in the lower part is raised to 600 F. which would represent approximately 300 of superheat and that the incoming mixture of liquid fuel and distribut-' ion is being ab-' stracted, by the mixture contacting therewith,

air contacting with the upper portion of the ring is absorbing suflicient heat to reduce the ring temperature to 400 R, which is still approximately 100 above satmration temperature. The steam in the bottom section of the ring will have a volume of 9.65- cubic feet per pound, while the steam in the upper section will have a volume of 7.7 cubic feet per pound, in other words, the heaviest steam will be at thetop of the ring.

Obviously, such a condition is unstable and will'cause circulation, or What is known as convection currents within the ring. The cooler steam from the top will flow to the bottom where heat is added and the hotter steamwilLris epn the opposite side of the ring to give up heattrrthencomin charge.

The exact condition within t ering-eaubp governed by proportioning the surface areas of those portions lying within the intake and exhaust manifolds. If high temperatures are desired, the portion within the exhaust manifold can be made large and that within the intake small. If the reverse condition is to the hot side of the ring to be re-evaporated. I

The latent heat of vaporization of steam at the assumed pressure of 50 lbs. per square inch is 911 B. t. u.s per pound. A pound of steam, therefore, at 298 F. will give up 911 B. t. u.s in changing to a pound of water 40 at the same pressure and temperature.

Where the ring is provided with a constriction, as illustrated in Figs. 5 and 6 or is made up of varying cross sections, in order to give varying surface areas, as just above described, the temperature of that portion of the ring within the intake manifold will always be approximately 298 F. This temperature can obviously be varied by varying the quantity of'water placed within the ring initially. If sufiicient water is placed within the ring to satisfy the conditions for 100 pounds gauge pressure, the resultant temperature of saturated steam will be 338 F.

In the form of heater element shown in Figs. 3 and 4, the heater will operate only at saturation temperatures. In this form, steam is produced in the vertical leg 21 and heat is absorbed from the horizontal leg 19 by the incoming mixture entering intake 20 of the inlet manifold.

In this L form of heater, the temperature in the horizontal-leg can rise to that corresponding to the pressure Which the water within the heater will maintain. The temperature of the leg 21 within the exhaust pasfull loads.

desired, the portion within the exhaust manisage may, however, rise to a much higher temperature and the steam therein may become superheated, but since substantially no circulation occurs, this will not be felt in the horizontal leg 19.

The heater element, no matter of which of the forms, can be sodesigned that with an increase in load, the heat absorbed by the mixture does not increase as rapidly as the quantity of mixtureincreases under increasing load with the result that as the load increases, the temperature of the mixture delivered .to the engine cylinders decreases. This is the ideal condition, since it insures the higliestatemperatures during fractional loads so and high 'volumetfidmotor etficjpncyduring Since the air is withdrawn from the ring or other form of heater element during its construction, the first heat absorbed produced steam which fills the entire element. The temperature of course, corresponds to the steam pressure. For instance, at one pound absolute pressure, the temperature of the element would be 100 F. and this would materially aid in Warming the mixture on a cold day. At seven pounds absolute pressure, the temperature would be 180 F. and at atmospher1c pressure, 212 F. The temperature continues to rise rapidly until the maximum is reached, for which the element is designed.

If 50 pounds is the maximum, then the maximum temperature would be 298 F.

It will be understood that practically any volatile fluid can be used within the heater element in place of water and if a form of heater is utilized in which rapid circulation can occur, a fixed gas may be employed in place of a volatile fluid.

It will be apparent that different internal 1 combustion engines have cylinders of dilferent size or displacement and that it may be desirable to designate different speeds of the same engine as those at which the engine is to operate with the best economy. It is, therefore, apparent that the rate of flow of the combustible mixture to the working passages of the engine not only varies in different designs of engine but that it varies in the same engine under different load or speed conditions. The rate of flow of combustible mixture, however, can be readily determined by engineers and this rate of flow can be readily determined for various conditions or assumed conditions of operation. If the engineer is careful to so design the intake passages of the engine that the mixture entering contacts or moves in close proximity with the heating element-i. e., the upper portion of the ring 12 of Figures 1 and 2 or the heat delivering leg 19 of the L-shaped tube of Figures 3 and 4-he can readily calculate or otherwise determine the rate of heat transfer under various assumed or encountered conditions and can thereby determine the appro- 'perature creases in temperature as the power developed priate volumetric capacity of the heating element, the quantity of water or other liquid to be confined therein and the appropriate areas to be exposed respectively to the source of heat and also within the intake passage in order to obtain the desired heat transfer to the mixture under the varying conditions encountered. It will be apparent that by taking advantage of my invention, the mixture may be quickly heated at the time of starting a cold engine and that the mixture entering the cylinders will be actually hotter under conditions of low speed or low powen than under conditions of operation selected for maximum economy, and that the mixture will decrease in temperature as the speed of the engine increases. It will also be apparent that while the temperature of the mixture heating element remains approximately constant under wide variations in the temof the exhaust gases it in fact deby the engine increases or as the source of heat-,-i. e., the exhaust gases,-gets hotter. With these facts in mind, it will be apparent that my inve'ntion'm'ay be employed in connection with internal combustion engines 0 various designs, and that it may also be employedtoobtainth best economies at difi'erp 7 r 7V v ture of liquid "fuel aiid'airto be delivered to i an internal combustion engine, comprising a ent speeds'in engines of'the same or identical design.

Having thus described my invention, what I claim is 1. The combination with means for delivering a mixture of liquid fuel and air to an internal combustion engine and means for conducting the exhaust gases therefrom, of a hollow, sealed, metallic element located partem is conveyed by the vaporized li tially within each of said means and a body of vaporizable liquid within said element and but partially filling the same; V

2. The combination with the intake and exhaust systems of an internal combustion engine, of a hollow metal device containing substantially no air and having but a small part of its interior filled with vaporizable liquid; said device bein sealed and located partly within each of sa1d systems so that heat from the exhaiist gases traversing the exhaust sysuid within the device to the mixture of liqui fuel and air traversing the intake system.

3. The combination with conduits for conducting exhaust gases from an internal com-L bastion engine and a mixture of liquid fuel and air to said engine, of a sealed metallic agent partly located within each of said conduits and containing a body of vaporizable liquid which when not vaporized fills but asmall part of such agent. V

4. The combination with the inlet manifold of an internal combustion engine, of a relatively thin walled metal container so positioned that one portion of the same is within and one portion outside of said manition of said tube fold, fluid sealed within said container and which in amount is relatively small when compared with the volumetric capacity of the container and means for applying sufficient heat to the container outside of said manifold to.

able liquid as compared with-the volumetric capacity of the hollow device; that portion of the device within the intake manifold being located in the path of the combustible mixture traversing said manifold and that portion located within the exhaust manifold being in the path of exhaust gases traversing said exhaust manifold whereby heat fromsaid exhaust gases is caused to vaporize said liquid and transfer heat from said exf haust gases to the combustible mixture traversing the intake manifold.

6. An apparatus for conditioning a mixdevice containing substanhaving but a small part of hollow metallic tially no air and its interior filled with vaporizable liquid,'said-' as the amount of the to the engine is in- 7. In combination with the combustible mixture delivery passages of an internal combustion engine, a sealed tube having a relatively small quantity of vaporizable liquid located therein and extending into said passage, means remote from said passage for the said liquid, the ecrease the temperigsw,

applying heat to said tube to va orize liquid contained therein, and means mixture moving through said delivery pas sage into heat exchange relation with the por extending into said passage. 8. In combination with an internal combustion engine and the combustible mixture delivery passages thereof, a sealed tube having a vaporizable liquid confined therein, extending into said inlet passage and so formed as to substantially prevent convection currents being set up therein, means remote from said passage for applying heat to said tube to vaporize the liquid contained therein, and means for directing the flow of mixture through said relation with the portion of said tube located in said passage.

assage into heat exchanging or directing I 9. In combination with an internal combustion engine and the combustible mixture delivery passage thereof, a sealed tube extending into said passage and having a vaporizable liquid confined therein, means remote from said passage for heating said tube to vaporize liquid contained therein, and means for substantiallychecking a convection flow of the vapor generated within said tube.

1 m 10. In combination with an internal combustioniengine and the fuel delivery passage thereof, a sealedtubd-extending into sa1d passage and having a vaporizableliquidcons tained therein, means for heating said tube 5 to vaporize liquid contained therein, and a -bafile within said tube for substantially pre.-' venting the setting up of convection currents within said tube.

11.- In combination with an internal combustion engine and the inlet and exhaust pasv sages thereof, a sealed tube containing a confined liquid exposed to the heat of the exhaust gases traversing said exhaust passage and extending into said inlet passage, and'means for directing the combustible mixture traversing said lnlet passage into heat exchanging relation with the portion of the tube located in said inlet passage. Y

12. In combination with an internal comso bustion engine and the inlet and exhaust gassages thereof, a heating element expose to the heat of exhaust gases traversing said exhaust passage and extending into said inlet passage, and means for maintaining the portion of said element in said inlet passage at an approximately constant temperature indepen ently of the amount of combustible mixture traversing said inlet assage.

' In testimony whereof, I have ereunto sub- 40 scribed my name this'lst day of April, 1926.

BRYANT BANNISTER. 

